Predictive Caching and Tunneling for Time-Sensitive Data Delivery to Roaming Client Devices

ABSTRACT

Techniques are provided for delivering data to a wireless client device in a wireless local area network via a plurality of access point devices as the wireless client device roams from one access point device to another. A wireless client device receives data communications (i.e., traffic) via a first wireless access point device in the wireless local area network. An impending roam of a wireless client device is detected. A set of one or more candidate wireless access point devices other than the first wireless access point device is determined to which the wireless client device may potentially roam. The one or more wireless access point devices in the set are assigned to a multicast group, and the traffic is sent to the multicast group.

TECHNICAL FIELD

The present disclosure relates to delivering data to wireless devicesvia access point devices in a network.

BACKGROUND

Wireless access point (APs) devices are deployed in network environmentsto serve wireless client devices. Each wireless AP is deployed to servethe wireless client devices in a coverage area. The APs can beconfigured to provide network access to the client devices via one ormore standard communication protocols, such as IEEE 802.11, knowncommercially as WiFi™. As the wireless client devices move, they mayassociate with different wireless APs to send and receive datacommunications. Thus, the traffic that had been sent to the client byone AP needs to be sent to it by a different AP.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B show example embodiments of a system topology includingone or more wireless client devices and a plurality of wireless accesspoint devices, in which predictive tunneling of traffic is performed forroaming client devices according to techniques presented herein.

FIG. 2 shows an example block diagram of a wireless controller deviceconfigured to enable sending of a copy of the client traffic to one ormore wireless access points to which a wireless client device maypotentially roam.

FIG. 3 shows an example block diagram of a wireless access point deviceconfigured to enable sending of client traffic to the one or morewireless access points to which the wireless client device maypotentially roam.

FIG. 4 shows an example timing of the predictive traffic tunneling andcaching techniques.

FIG. 5 shows an example flow chart depicting operations associated withthe predictive tunneling and caching techniques.

DESCRIPTION OF EXAMPLE EMBODIMENTS Overview

Techniques are presented herein for delivering data to a wireless clientdevice in a wireless local area network via a plurality of access pointdevices as the wireless client device roams from one access point deviceto another. A wireless client device receives data communications (i.e.,traffic) via a first wireless access point device in the wireless localarea network. An impending roam of a wireless client device is detected.A set of one or more candidate wireless access point devices other thanthe first wireless access point device is determined to which thewireless client device may potentially roam. The one or more wirelessaccess point devices in the set are assigned to a multicast group, andthe traffic is sent to the multicast group.

Example Embodiments

The techniques described herein relate to delivering data communications(also generically referred to herein as “traffic”) to wireless devicesin a network. An example network topology 100 is illustrated in FIGS. 1Aand 1B. The topology 100 (hereinafter “network topology,” “wirelessnetwork” or “network”) comprises a plurality of wireless access pointdevices (“wireless access points” or “wireless APs”). The wirelessaccess points are shown at reference numerals 102(1)-102(n). The network100 also has one or more wireless client devices, shown at referencenumerals 104(1)-104(m). In one embodiment, as shown in FIG. 1A, thewireless access points 102(1)-102(n) are configured to communicate witha wireless controller device 106 (“wireless controller”) using, forexample, a Control and Provisioning of Wireless Access Points (CAPWAP)protocol as specified by the Internet Engineering Task Force (IETF)Request for Comments (RFC) 5415. In the embodiment of FIG. 1A, thewireless controller 106 is configured to communicate with a branchrouter device 108, and the branch router device 108 is coupled to a widearea network (WAN) 110, e.g., the Internet. In the embodiment of FIG.1B, the wireless access points 102(1)-102(n) communicate directly withthe branch router device 108 (e.g., using the CAPWAP protocol) that, inturn, communicates with the wireless controller 106 across the WAN 110.

In one example, the wireless access point devices 102(1)-102(n) in FIGS.1A and 1B are located in a geographic area (e.g., a corporate officebuilding), while the wireless controller 106 and the branch router 108may be located at a remote location (e.g., a central office located at adistance away from the corporate office building). For example, thewireless access point devices 102(1)-102(n) may be deployed as hybridremote edge access point (H-REAP) devices such that the wireless accesspoints 102(1)-102(n) are deployed locally without requiring a wirelesscontroller 106 to be present in the local area of the wireless accesspoints.

The network 100 is configured to provide traffic (e.g., audio, videoand/or any type of data communications) to the wireless client devices104(1)-104(m) via the wireless access points 102(1)-102(n). The contentfor the traffic may originate, for example, from a local server or froma server or device (e.g., web server) connected to the WAN 110. Forsimplicity, the source of the content is not shown in FIGS. 1A and 1B.

Each of the wireless access points 102(1)-102(n) is configured towirelessly transmit the traffic to the wireless client devices104(1)-104(m) over a coverage area. That is, each of the wireless accesspoints 102(1)-102(n) may transmit the traffic to one or more of thewireless client devices 104(1)-104(m) when the wireless client devicesare located within a corresponding coverage area or range of acorresponding one of the wireless access points. When a particularwireless access point transmits traffic to a particular wireless clientdevice, the client device is said to be “associated” to or with thatparticular wireless access point. The wireless access points102(1)-102(n) may be, for example, wireless access points that deliverdata to the wireless client devices 104(1)-104(m) from a network usingwireless local area network standards now known or hereinafterdeveloped.

The wireless client devices 104(1)-104(m) may be mobile devices (e.g.,mobile phones, computers, laptops, tablets, etc.) that are capable ofreadily moving (roaming) to change locations in the wireless network 100relative to the wireless access points 102(1)-102(n). Thus, as awireless client device roams or changes location within the network 100,the wireless client device may be associated with a different wirelessaccess point based on its relative location to the wireless accesspoints 102(1)-102(n). For example, as shown at reference numeral 112 inFIGS. 1A and 1B, wireless client device 104(2) may initially beassociated to wireless access point 102(1) but may move and later becomeassociated to wireless access point 102(3). Thus, before the wirelessclient device 104(2) roams, the wireless client device 104(2) sends andreceives traffic via the wireless access point 102(1), and after thewireless client device 104(2) roams, it sends and receives traffic viathe wireless access point 102(3).

As a wireless client device roams within the network 100, otherequipment in the network (e.g., the wireless controller 106 and/or oneor more of the wireless access points 102(1)-102(n)) ensures that datacommunications are seamlessly provided to the wireless client device asit associates with a different one of the wireless access point devices102(1)-102(n). These techniques are described in detail hereinafter.

Briefly, according to the techniques presented herein, an impending roamevent of a wireless client device is detected, and a set of one or morewireless access points to which the wireless client device is likely toroam is determined. The one or more wireless access points in this setare referred to as candidate access points and they are assigned to amulticast group. Prior to actually roaming by the wireless clientdevice, the client traffic for the wireless client device (that is beingwirelessly transmitted to the client device by the access point deviceto which the client device is currently associated with) is (copied and)sent to the multicast group (i.e., to a multicast group address for themulticast group) so that each of the access point devices in the set ofcandidate access point devices will receive and store the traffic. Thus,the access point devices in the candidate set will have traffic for theclient before the client has even roamed to any one of those accesspoint devices. As will be described hereinafter with reference back toFIGS. 1A and 1B, the wireless controller 106 may direct these operationsaccording to one embodiment shown in FIG. 1A, or the access point towhich the client is currently associated may direct these operations, asdepicted in FIG. 1B.

Reference is now made to FIG. 2. FIG. 2 shows an example block diagramof the wireless controller 106 that is configured to direct thepredictive tunneling operations according to the embodiment depicted inFIG. 1A. The wireless controller 106 comprises, among other components,a network interface unit 204, a processor 206 and a memory 208. Thenetwork interface unit 204 is configured to receive data communicationsfrom devices in the network 100 and to send data communications todevices in the network. For example, the network interface unit 204 isconfigured to send and receive data communications from the branchrouter 108, the wireless access points 102(1)-102(n) and the wirelessclient devices 104(1)-104(m). The network interface unit 204 is coupledto the processor 206. The processor 206 is, for example, amicroprocessor or microcontroller that is configured to execute programlogic instructions (i.e., software) for carrying out various operationsand tasks of the controller device 106, as described herein. Forexample, the processor 206 is configured to execute roaming detectionand tunneling process logic 210 to send data communications to amulticast group of access point devices to ensure a seamless delivery ofdata communications to the wireless client devices 104(1)-104(m). Thefunctions of the processor 206 may be implemented by logic encoded inone or more tangible computer readable storage media or devices (e.g.,storage devices, compact discs, digital video discs, flash memorydrives, etc. and embedded logic such as an application specificintegrated circuit, digital signal processor instructions, software thatis executed by a processor, etc.).

The memory 208 may comprise read only memory (ROM), random access memory(RAM), magnetic disk storage media devices, optical storage mediadevices, flash memory devices, electrical, optical, or otherphysical/tangible (non-transitory) memory storage devices. Thus, ingeneral, the memory 208 may comprise one or more computer readablestorage media (e.g., a memory storage device) encoded with softwarecomprising computer executable instructions and when the software isexecuted (e.g., by the processor 206) it is operable to perform theoperations described for the roaming detection and tunneling processlogic 210.

The process logic 210 may take any of a variety of forms, so as to beencoded in one or more tangible computer readable memory media orstorage devices for execution, such as fixed logic or programmable logic(e.g., software/computer instructions executed by a processor), and theprocessor 206 may be an application specific integrated circuit (ASIC)that comprises fixed digital logic, or a combination thereof.

For example, the processor 206 may be embodied by digital logic gates ina fixed or programmable digital logic integrated circuit, which digitallogic gates are configured to perform the operations of the processlogic 210. In general, the roaming detection and tunneling process logic210 may be embodied in one or more computer readable storage mediaencoded with software comprising computer executable instructions andwhen the software is executed operable to perform the operationsdescribed hereinafter.

Reference is now made to FIG. 3. FIG. 3 shows a block diagram 102 of oneof the wireless access point devices 102(1)-102(n), that is configuredto participate in, and optionally direct, the traffic tunnelingoperations according to the embodiment on FIG. 1B. It should beappreciated that the block diagram 102 in FIG. 3 may be any of thewireless access point devices 102(1)-102(n), and for simplicity, thewireless access point in FIG. 3 is referred to generally as “wirelessaccess point 102.” The wireless access point device 102 comprises, amongother components, an antenna 304, a receiver 306, a transmitter 308, amodem 310, a processor 312 and a memory 314. The receiver 306 of theaccess point device 102 receives wireless communications from devices inthe network 100 (e.g., the wireless client devices 104(1)-104(m)) viathe antenna 304. Likewise, the transmitter 308 of the access pointdevice 102 wirelessly transmits communications to client devices via theantenna 304. The receiver 306 and the transmitter 308 may be embodied inone or more integrated circuits, and are coupled to the modem 310. Themodem 310 is configured to modulate signals to be transmitted by thetransmitter 308 and to demodulated signals received by the receiver 306.The modem 310 may also be embodied in an integrated circuit, and iscoupled to the processor 312. The processor 312 may be a microprocessoror microcontroller. In one example, the processor 312 is configured toexecute roaming detection and tunneling process logic 320, stored inmemory 314, to send data communications to a multicast group of accesspoint devices to ensure a seamless delivery of data communications to aroaming wireless client device for the embodiment of FIG. 1B.Additionally, memory 314 has a data communication cache 322 that isallocated to store data communications (traffic) sent to it by thewireless controller 106 or by another access point as part of thepredictive caching and tunneling procedure described herein. In otherwords, any access point device that is to be capable of participating inthe predictive caching and tunneling techniques as an access pointdevice that can receive traffic will have some portion of its memoryallocated to cache traffic. However, any access point device that is tobe capable of directing the predictive caching and tunneling techniquesto one or more other access points will be configured with roamingdetection and tunneling process logic 320

Referring back to FIGS. 1A and 1B, in general, traffic is delivered tothe wireless client devices 104(1)-104(m) as they roam and associatewith different wireless access points in the network 100. As describedabove, the wireless access points 102(1)-102(n) in the network 100 maybe arranged in an H-REAP configuration, and thus, the wireless accesspoints 102(1)-102(n) retrieve the data communications from the wirelesscontroller 106 remotely across the WAN 110. Since the traffic is sentfrom the wireless controller 106 across the WAN 110, there may be delaysin the wireless access points 102(1)-102(n) receiving traffic andsending the packets (of the traffic) to the appropriate one of thewireless client devices 104(1)-104(n). For certain data communications,these delays sometimes may be tolerable (e.g., web browsing, email,etc.), but some content may be more time-sensitive (e.g., isochronousdata such as audio and/or video data), and thus, the delays in the datacommunications may present an undesirable experience for users at one ormore of the wireless client devices 104(1)-104(m).

These delays may be exacerbated as the wireless client devices104(1)-104(m) roam and associate with different wireless access points102(1)-102(n) in the network 100. For example, the wireless clientdevice 104(2) is associated to wireless access point 102(1) and isreceiving video data from the wireless access point 102(1). When theclient device 104(2) roams and associates to a new wireless access point(e.g., wireless access point 102(3)), the wireless client device 104(2)may have to establish authentication and association exchanges with thenew wireless access point before it can begin receiving traffic from theaccess point 102(3). After associating with the new wireless accesspoint, the wireless client device 104(2) then may have to re-negotiate arequest for the video data via the new wireless access point. Often, asthe wireless client device 104(2) is performing the authentication,association and requesting operations, the data buffer of the wirelessclient device 104(2) may be emptied before the video data transmissionis resumed. Thus, the user of the wireless client device 104(2)experiences delays or disruptions in receiving the stream of data (e.g.,video, audio, etc.).

The techniques described herein overcome these problems by distributingthe client bound traffic to a set of one or more wireless access pointdevices to which it is determined that the client device is likely toroam. These techniques are described in connection with two embodiments.In the embodiment of FIG. 1A, the wireless controller 106 is configuredto detect an impending roam of a wireless client device, and upondetecting the impending roam, the wireless controller 106 sends theclient bound traffic for that client device to a set of one or moreaccess points to which the wireless client device may potentially roamto be cached by the set of one or more access points. In the embodimentof FIG. 1B, one of the wireless access points (e.g., the access point towhich the client device is currently associated) detects the impendingroam and sends the traffic to the set of one or more access points towhich the wireless client device may roam (to be cached by the set ofone or more access points).

The first embodiment of FIG. 1A is now described. Referring to FIG. 1A,the wireless controller 106 detects an impending roam by informationreceived from one or more of the wireless client devices 104(1)-104(m).For example, as the wireless client device 104(2) (initially associatedto wireless access point 102(1)) moves in the network 100, the wirelesscontroller 106 may obtain a received signal strength indication (RSSI)measurement made by access point 102(1) for signals sent between it andthe wireless client device 104(2) and the wireless access point 102(1).If the RSSI level is below a threshold, the wireless controller 106 maydetermine that an impending roam is about to occur (e.g., indicatingthat the wireless client device 104(2) will soon be associating to a newwireless access point other than the wireless access point 102(1)).

Once this impending roam is detected, the wireless controller 106determines a set of one or more candidate wireless access points (otherthan the wireless access point 102(1)) to which the wireless clientdevice 104(2) may potentially roam. The wireless controller 106 maydetermine this set of candidate access points by, for example,determining a location of the wireless client device 104(2) relative tothe location of the wireless access points 102(2)-102(n) based on signalmeasurement date obtained from multiple access points. A wireless accesspoint may be included in the set of candidate access points if it iswithin a predetermined distance of the wireless client device 104(2).The wireless controller 106 may maintain a list of wireless accesspoints that neighbor every other wireless access point. Thus, thewireless controller 106 can determine which of these neighboringwireless access points have recently received probe requests from thewireless client device 104(2). The probe requests may indicate that thewireless client device 104(2) may potentially roam to a particularwireless access point, and thus the wireless controller 106 may be ableto determine the directional nature of roaming activity of the wirelessclient device 104(2).

In another example, the wireless controller 106 may evaluate a roaminghistory of the wireless client device 104(2) to predict future roamingtendencies of the wireless client device based on observed movementpatterns of a particular client device over time. Additionally, thewireless controller 106 may determine the set of wireless access pointsby evaluating the RSSI between the wireless client device 104(2) andeach of the wireless access points 102(2)-102(n), respectively. If theRSSI is above a predetermined threshold for an access point device, thecorresponding wireless access point may be included in the set ofcandidate access point devices. Other metrics may be used to predictfuture roaming tendencies, for example, client location, packet errorratios of data transmissions and physical layer data changes. Forexample, in FIG. 1A, as the wireless client device 104(2) moves in thenetwork, the wireless controller 106 includes wireless access point102(2) and wireless access point 102(3) in the set of candidate wirelessaccess points to which the wireless client device 104(2) may potentiallyroam (shown at reference A). Wireless access point 102(n), however, isnot included in this set.

Once the wireless controller 106 determines the set of candidatewireless access points to which the wireless client device 104(2) mayroam, the wireless controller 106 assigns the wireless access points inthe set to a multicast group (with a corresponding multicast groupaddress) and creates a dynamic multicast communication tunnel (e.g., amulticast CAPWAP tunnel). By establishing the multicast group, thewireless controller 106 is then able to prepare the wireless accesspoints in the multicast group for the association and application flowtransition for the roaming client device (the wireless client device104(2)). That is, to reduce service interruption, a profile of theroaming client device is sent to the wireless access points in themulticast group by the wireless controller 106 in order to facilitatethe set up of a communication link between the roaming client device andthe wireless access points. The information in the profile of theroaming client device may include association information of the roamingclient device (e.g., to reduce link setup time on the new wirelessaccess point after the roaming client has camped on to a new wirelessaccess point) and time-sensitive application flow context information ofthe roaming client device (e.g., to enable the new wireless access pointto start accepting and buffering the data communications for existingactive data flows to the roaming client). In one example, theassociation information may include client quality of service (QoS)profiles, client ongoing traffic QoS profiles and states, IP addressassignment for the client and encryption key information for the client.

At this point, the wireless client device 104(2) is still associated towireless access point 102(1) and is still receiving traffic via thewireless access point device 102(1). After the wireless controller 106sends the profile information to the multicast group of wireless accesspoints, the wireless controller 106 sends (a copy of) the client traffic(also currently being sent to the wireless client device 104(2)) to themulticast group address for the multicast group of wireless accesspoints. The traffic is sent to the wireless access points in themulticast group via, for example, a multicast CAPWAP tunnel that isestablished between each wireless access point in the multicast groupand the wireless controller 106 (if one is not already created). Forexample, the wireless controller 106 populates the multicast address ofthe multicast tunnel such that when wireless access points join themulticast group, they receive the traffic as multicast communicationsfrom the wireless controller 106. In other words, the wirelesscontroller 106 utilizes the multicast group to tunnel unicast datacommunications in a dynamic multicast tunnel to the wireless accesspoints in the multicast group. The multicast tunnel is shown atreference B.

Once the wireless access points in the multicast group receive thetraffic, they store/cache the data for the traffic, e.g., in cache 322referred to above in connection with FIG. 3. In one example, eachwireless access point in the multicast group may store a predeterminedamount of the traffic (e.g., a predetermined amount or number of minutesof video and/or audio data). If any of the wireless access points in themulticast group receives more than the predetermined amount of trafficthan it can store it may discard the older portions of the cachedtraffic. Thus, for example, if the wireless access points in themulticast group are configured to store five seconds of video data inthe data communications cache 322, and if the wireless access pointsreceive seven seconds of video data (before the wireless client device104(2) roams), each of the wireless access points will discard theoldest two seconds of the video data from the data communications cache322.

As stated above, until this point, the wireless client device 104(2) hasassociated to a new wireless access point. That is, the actionsdescribed above occur when there is an impending roam. After thewireless client device 104(2) associates with a new wireless accesspoint (e.g., the wireless access point 102(3)), the new wireless accesspoint can begin sending the cached traffic to the wireless client device104(2). For example, the new wireless access point may be able to sendits cached traffic at the most recent point at which data communicationsfrom the previous wireless access point (wireless access point 102(1))left off. In one example, the wireless controller 106 sends a messagecontaining, for example, a real time transport protocol (RTP) sequencenumber, a CAPWAP packet sequence number, a layer 4 (and above) sequencenumber, etc. that provides a synchronized context to enable a seamlesstransition of data communications to the wireless client device 104(2).This message may be sent using a CAPWAP protocol.

Additionally, after the wireless client device 104(2) roams to the newwireless access point, the wireless controller 106 terminates sending ofthe traffic to the multicast group. Instead, traffic is sent unicastonly to the new wireless access point. If the wireless controller 106detects a further impending roam, it repeats the operations describedabove to generate a new set of candidate wireless access points to whichthe wireless client device 104(2) may roam.

A similar predictive tunneling scheme can be achieved when the wirelesscontroller 106 is not in the best position to direct it, as explained inthe second embodiment, which is now described in reference to FIG. 1B.In this embodiment, the predictive tunneling is performed by an accesspoint to which the client device is currently (last) associated. Inother words, in the second embodiment, the operations that are performedby the wireless controller 106 in the first embodiment may be performedby this access point. For example, the wireless access point 102(1)detects the impending roam of the wireless client device 104(2) (e.g.,by measuring and evaluating the RSSI between it and the wireless clientdevice 104(2)). After detecting the impending roam of client device104(2), the wireless access point 102(1) determines a set of one or morecandidate wireless access points other than the wireless access point102(1) to which the wireless client 104(2) may potentially roam, usingany of the techniques described above in connection with the wirelesscontroller 106 directed embodiment depicted in FIG. 1B. The wirelessaccess point 102(1) then assigns the wireless access points in the setto a multicast group and sends the profile of the wireless client device104(2) to these wireless access points. The access point 102(1) sendstraffic to the multicast group in a CAPWAP tunnel (in a manner similarto that described above for the wireless controller) to enable thewireless access points in the multicast group to cache a predeterminedamount of the traffic data. After the wireless client device 104(2)roams to a new wireless access point (e.g., wireless access point102(3)), the new access point can transmit its cached data to the clientdevice 104(2). Additionally, the wireless access point 102(1) terminatessending of traffic to the multicast group. After the roam is completed,the wireless controller will thereafter take over unicasting traffic tothe new wireless access point.

Reference is now made to FIG. 4. FIG. 4 shows an example depiction of atiming 400 of traffic delivered to various wireless access points102(1)-102(n) (and ultimately to the wireless client device 104(2)) inthe network 100 in a roaming scenario. The embodiments of FIGS. 1A and1B are contemplated by the timing 400. It should be appreciated that thetime instances shown in FIG. 4 are merely examples.

The first time line, shown at reference numeral 410, depicts datatransmissions to the wireless access point (e.g., the wireless accesspoint 102(1)) to which the wireless client device 104(2) is currentlyassociated. As shown, at time t=1, the wireless controller sends trafficunicast to the wireless access point 102(1) for wireless transmission tothe wireless client device 104(2). At time t=3, an impending roam of thewireless client device 104(2) is detected. Thus, as shown in referencenumeral 420, traffic for the client is multicasted to the wirelessaccess points that are in a set of potential wireless access points towhich the wireless client device 104(2) may roam. Some time later, asshown at 430, at time t=x, the wireless client device 104(2) roams to anew wireless access point, and the traffic is sent unicast to thewireless access point to which the wireless client device associates forultimate delivery to the wireless client device. At time t=y, thewireless client device 104(2) terminates the data communication session.

Reference is now made to FIG. 5. FIG. 5 shows an example flow chart 500depicting operations of the roaming detection and tunneling techniquesto enable seamless transfer of data communications from one wirelessaccess point to another wireless access point. These operations may beperformed by the wireless controller 106 and/or by one or more of thewireless access points 102(1)-102(n) in the network 100, as describedabove. At operation 510, an impending roam is detected of a wirelessclient device that receives traffic via a first wireless access pointdevice in a wireless local area network. At operation 515, a set of oneor more candidate wireless access point devices, other than the firstwireless access point device, to which the wireless client device maypotentially roam is determined. These one or more wireless access pointdevices in the set are assigned, at operation 520, to a multicast group,and at operation 525, the traffic is sent to the multicast tunnel formedby the multicast group such that each of the wireless access pointdevices in the set stores the traffic. Thereafter, when the clientdevice has roamed to one of the access points in the set, that accesspoint wirelessly transmits the cached traffic to enable a seamlessdelivery of the traffic to the client device. The other access points inthe set can discard the traffic that they have cached after apredetermined period of time indicating that the client device did notroam to them.

It should be appreciated that the techniques described above inconnection with all embodiments may be performed by one or more computerreadable storage media that is encoded with software comprising computerexecutable instructions to perform the methods and steps describedherein. For example, the operations performed by the wireless controller106 and/or one or more of the wireless access points 102(1)-102(n) maybe performed by one or more computer or machine readable storage media(non-transitory) or device executed by a processor and comprisingsoftware, hardware or a combination of software and hardware to performthe techniques described herein.

In summary, a method is provided comprising: detecting an impending roamof a wireless client device that receives data communications via afirst wireless access point device in a wireless local area network;determining a set of one or more of wireless access point devices otherthan the first wireless access point device to which the wireless clientdevice may potentially roam; assigning the one or more wireless accesspoint devices in the set to a multicast group; and sending the datacommunications to the multicast group.

In addition, one or more computer readable storage media encoded withsoftware is provided comprising computer executable instructions andwhen the software is executed operable to: detect an impending roam of awireless client device that receives data communications via a firstwireless access point device in a wireless local area network; determinea set of one or more wireless access point devices other than the firstwireless access point device to which the wireless client device maypotentially roam; assign the one or more wireless access point devicesin the set to a multicast group; and send the data communications to themulticast group.

Furthermore, an apparatus is provided comprising: a network interfaceunit configured to enable communications over a network; a memory; and aprocessor coupled to the network interface unit and the memory unit andconfigured to: detect an impending roam of a wireless client device thatreceives data communications via a first wireless access point device ina wireless local area network; determine a set of one or more wirelessaccess point devices other than the first wireless access point deviceto which the wireless client device may potentially roam; assign the oneor more wireless access point devices in the set to a multicast group;and send the data communications to the multicast group.

The above description is intended by way of example only. Variousmodifications and structural changes may be made therein withoutdeparting from the scope of the concepts described herein and within thescope and range of equivalents of the claims.

What is claimed is:
 1. A method comprising: detecting an impending roamof a wireless client device that receives data communications via afirst wireless access point device in a wireless local area network;determining a set of one or more of wireless access point devices otherthan the first wireless access point device to which the wireless clientdevice may potentially roam; assigning the one or more wireless accesspoint devices in the set to a multicast group; and sending the datacommunications to the multicast group.
 2. The method of claim 1, furthercomprising sending client profile information to each of the wirelessaccess point devices in the set to facilitate set up of communicationbetween the wireless client device and a new wireless access pointdevice.
 3. The method of claim 2, further comprising creating a dynamicmulticast tunnel for the set of wireless access point devices if thereis not a tunnel already created, and populating a multicast address ofthe tunnel together with the flow context information so that the set ofwireless access point devices will join the multicast group and receivethe data communications.
 4. The method of claim 2, wherein the clientprofile information further includes flow context information thatenables the wireless access point devices in the set to start acceptingand buffering data for existing active flows to the wireless clientdevice.
 5. The method of claim 2, further comprising sending to the newwireless access point device a message containing a synchronized contextto enable the new wireless access point device to send stored data tothe wireless client device from a point where the first wireless accesspoint device left off.
 6. The method of claim 5, wherein sending themessage containing the synchronized context comprises sending one of: areal time transport protocol (RTP) sequence number, a control andprovisioning of wireless access points (CAPWAP) sequence number and aLayer 4 protocol sequence number.
 7. The method of claim 5, after theclient device completes its roaming to the new wireless access pointdevice, further comprising terminating sending of data communicationsfor the client device to the multicast group, and sending unicast datacommunications for the client device to the new wireless access pointdevice.
 8. The method of claim 1, wherein the data communicationscomprise a video stream or an audio stream.
 9. The method of claim 1,wherein detecting, determining, assigning and sending are performed at awireless network controller that is in communication with the pluralityof wireless access point devices in the wireless network.
 10. The methodof claim 1, wherein detecting the impending roam comprises: receivinginformation of a received signal strength indication (RSSI) signalbetween the wireless client device and the first wireless access pointdevice; and determining the impending roam when the RSSI signaldecreases below a threshold signal strength.
 11. The method of claim 1,wherein detecting, determining, assigning and sending are performed atthe first wireless access point device.
 12. A computer-readable storagemedia encoded with software comprising computer executable instructionsand when the software is executed operable to: detect an impending roamof a wireless client device that receives data communications via afirst wireless access point device in a wireless local area network;determine a set of one or more wireless access point devices other thanthe first wireless access point device to which the wireless clientdevice may potentially roam; assign the one or more wireless accesspoint devices in the set to a multicast group; and send the datacommunications to the multicast group.
 13. The computer-readable storagemedia of claim 12, further comprising instructions operable to sendclient profile information to each of the wireless access point devicesin the set to facilitate set up of communication between the wirelessclient device and a new wireless access point device.
 14. Thecomputer-readable storage media of claim 13, further comprisinginstructions operable to create a dynamic multicast tunnel for the setof wireless access point devices if there is not a tunnel alreadycreated, and populate a multicast address of the tunnel together withthe flow context information so that the set of wireless access pointdevices will join the multicast group and receive the datacommunications.
 15. The computer-readable storage media of claim 13,further comprising instructions operable to send to the new wirelessaccess point device a message containing a synchronized context toenable the new wireless access point device to send stored data to thewireless client device from a point where the first wireless accesspoint device left off.
 16. The computer-readable storage media of claim15, wherein the instructions operable to send the message containing thesynchronized context comprises instructions operable to send one of: areal time transport protocol (RTP) sequence number, a control andprovisioning of wireless access points (CAPWAP) sequence number and aLayer 4 protocol sequence number.
 17. The computer readable storagemedia of claim 15, further comprising instructions operable to:terminate sending of data communications for the client device to themulticast group after the client device completes its roaming to the newwireless access point device; and send unicast data communications forthe client device to the new wireless access point device.
 18. Thecomputer-readable storage media of claim 12, wherein the instructionsoperable to detect the impending roam comprise instructions operable to:receive information of a received signal strength indication (RSSI)signal between the wireless client device and the first wireless accesspoint device; and determine the impending roam when the RSSI signaldecreases below a threshold signal strength.
 19. An apparatuscomprising: a network interface unit configured to enable communicationsover a network; a memory; and a processor coupled to the networkinterface unit and the memory and configured to: detect an impendingroam of a wireless client device that receives data communications via afirst wireless access point device in a wireless local area network;determine a set of one or more wireless access point devices other thanthe first wireless access point device to which the wireless clientdevice may potentially roam; assign the one or more wireless accesspoint devices in the set to a multicast group; and send the datacommunications to the multicast group.
 20. The apparatus of claim 19,wherein the processor is further configured to send client profileinformation to each of the wireless access point devices in the set tofacilitate set up of a communication link between the wireless clientdevice and a new wireless access point device.
 21. The apparatus ofclaim 20, wherein the processor is further configured to create adynamic multicast tunnel for the set of wireless access point devices ifthere is not a tunnel already created, and populate a multicast addressof the tunnel together with the flow context information such that theset of wireless access point devices will join the multicast group andreceive the data communications.
 22. The apparatus of claim 20, whereinthe processor is further configured to send to the new wireless accesspoint device a message containing a synchronized context to enable thenew wireless access point device to send stored data to the wirelessclient device from a point where the first wireless access point deviceleft off.